>From 986114bf211d5f4ce1d53cd054119cf035154324 Mon Sep 17 00:00:00 2001
From: Richard Dale <richard dale codethink co uk>
Date: Fri, 8 Jun 2018 11:06:12 +0100
Subject: [PATCH] Add support for Git LFS repositories

Use 'git lfs ls-files <ref>' to determine whether
or not there are any files under lfs control in
the target branch.

If there are files stored in git lfs, then change
the origin URL to be the upstream one, rather than
the local cached bare repo.

This approach works, but it would be better to leave
the origin URL, and instead add an .lfsconfig file
that points to the lfs object store. However, I couldn't
find a way of doing this without get a user/password
prompt from git.
---
 buildstream/plugins/sources/git.py | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/buildstream/plugins/sources/git.py b/buildstream/plugins/sources/git.py
index d079d87..06d6517 100644
--- a/buildstream/plugins/sources/git.py
+++ b/buildstream/plugins/sources/git.py
@@ -82,6 +82,7 @@ from buildstream import Source, SourceError, Consistency
 from buildstream import utils
 
 GIT_MODULES = '.gitmodules'
+GIT_ATTRIBUTES = '.gitattributes'
 
 
 # Because of handling of submodules, we maintain a GitMirror
@@ -138,6 +139,12 @@ class GitMirror():
         rc = self.source.call([self.source.host_git, 'cat-file', '-t', self.ref], cwd=self.mirror)
         return rc == 0
 
+    def ref_expects_lfs(self):
+        if not self.has_ref():
+            return False
+        exit_code, files = self.source.check_output([self.source.host_git, 'lfs', 'ls-files', self.ref], cwd=self.mirror)
+        return exit_code == 0 and len(files) > 0
+
     def assert_ref(self):
         if not self.has_ref():
             raise SourceError("{}: expected ref '{}' was not found in git repository: '{}'"
@@ -159,6 +166,12 @@ class GitMirror():
         self.source.call([self.source.host_git, 'clone', '--no-checkout', '--no-hardlinks', self.mirror, fullpath],
                          fail="Failed to create git mirror {} in directory: {}".format(self.mirror, fullpath))
 
+        expects_lfs = self.ref_expects_lfs();
+        if expects_lfs:
+            self.source.warn("{}: ref expects lfs '{}'"
+                             .format(self.source, self.ref))
+            self.set_origin_url(directory)
+
         self.source.call([self.source.host_git, 'checkout', '--force', self.ref],
                          fail="Failed to checkout git ref {}".format(self.ref),
                          cwd=fullpath)
@@ -241,6 +254,14 @@ class GitMirror():
 
             return None
 
+    def set_origin_url(self, directory):
+        fullpath = os.path.join(directory, self.path)
+        _, origin_url = self.source.check_output([self.source.host_git, 'config', '--get', 'remote.origin.url'],
+                         fail='Failed to get origin url "{}"'.format(self.mirror),
+                         cwd=self.mirror)
+        self.source.call([self.source.host_git, 'config', 'remote.origin.url', origin_url],
+                         fail="Failed to set origin url {}".format(origin_url),
+                         cwd=fullpath)
 
 class GitSource(Source):
     # pylint: disable=attribute-defined-outside-init
@@ -432,7 +453,6 @@ class GitSource(Source):
                 mirror.fetch()
                 mirror.assert_ref()
 
-
 # Plugin entry point
 def setup():
     return GitSource
-- 
2.7.4